India's strategic need of having a nuclear triad is close to becoming a reality with the commissioning of INS Arihant, India's first indigenously built nuclear submarine. Once it is official, India will be entering an elite group that has the power to launch nuclear attack from land, air and sea.

The nuclear armed submarine was quietly commissioned into the Indian Navy in August 2016, according to News X.

The INS Arihant project is controlled directly by the Prime Minister's Office and hence very little information is available about it, apart from the skeletal facts released to the media.

INS Arihant, a 6,000-tonne submarine, is propelled by an 83 MW pressurised light-water reactor at its core. It has undergone deep sea dives off Vishakhapatnam coast and other requisite sea trails.

The submarine can be equipped with K-15 (700km range) short range missiles and K-4 ballistic missile (3,500km) long range missiles.

"It has passed all tests and in many things has surpassed our expectations," the Economic Times reported quoting officials.

However, the submarine is not "fully ready" for deterrent patrols yet, the Times of India reported quoting sources.

Arihant is expected to be used in the event of a nuclear strike, bolstering India's second-strike ability. The Arihant can stay underwater for months and can lurk in the sea secretly.

It is the first of the three nuclear armed submarines to be manufactured indigenously. Reports have said that the construction of the second one, INS Aridhaman is expected to be over soon. It is likely to be delivered to the Indian Navy in 2018 for further trails.

Currently, only the US, UK, Russia, France and China have such capability.

India has been a "responsible" nuclear power with a "no first-use" policy in comparison with its neighbour Pakistan that has always threatened about nuclear war when tensions simmer between the two countries.